When working with complex state management in React applications, computed properties can be incredibly useful. Computed properties allow us to derive values from existing state, making data manipulation and rendering more efficient.

In this blog post, we will explore how to use computed properties with the Immer library in a React application. Immer is a powerful state management library that allows us to work with immutable state in a more convenient and intuitive way.

Setting up the project

Before diving into the usage of computed properties, let’s set up a basic React project with Immer.

1. Create a new React project using Create React App: npx create-react-app my-project.
2. Install Immer as a dependency:

npm install immer

1. Create a new file called store.js in the src directory:

import produce from 'immer';

export const initialState = {
  counter: 0
};

export const reducer = produce((draft, action) => {
  switch (action.type) {
    case 'INCREMENT':
      draft.counter += 1;
      break;
    case 'DECREMENT':
      draft.counter -= 1;
      break;
    default:
      break;
  }
}, initialState);

Using computed properties with Immer

Now that we have set up our project, let’s see how we can leverage computed properties with Immer in a simple counter application.

1. Import the useImmerReducer hook from Immer in your App.js file:

import { useImmerReducer } from 'immer';

1. Update the App component to use the useImmerReducer hook:

function App() {
  const [state, dispatch] = useImmerReducer(reducer, initialState);

  // Your component code...

  return (
    <div>
      <h1>Counter: {state.counter}</h1>
      <button onClick={() => dispatch({ type: 'INCREMENT' })}>Increment</button>
      <button onClick={() => dispatch({ type: 'DECREMENT' })}>Decrement</button>
    </div>
  );
}

1. Now, we can define our computed property using a simple function inside the reducer:

const reducer = produce((draft, action) => {
  switch (action.type) {
    case 'INCREMENT':
      draft.counter += 1;
      break;
    case 'DECREMENT':
      draft.counter -= 1;
      break;
    default:
      break;
  }

  draft.isPositive = draft.counter > 0; // Computed property

}, initialState);

1. Finally, we can render the computed property in our component:

return (
    <div>
      <h1>Counter: {state.counter}</h1>
      <h2>{state.isPositive ? 'Positive' : 'Negative'}</h2>
      <button onClick={() => dispatch({ type: 'INCREMENT' })}>Increment</button>
      <button onClick={() => dispatch({ type: 'DECREMENT' })}>Decrement</button>
    </div>
  );

Conclusion

Computed properties are a powerful tool in managing complex state in React applications. By leveraging the Immer library, we can easily create and update computed properties in an immutable and understandable way.

Using computed properties with Immer not only simplifies our code but also enhances the overall performance of our React application.

Remember to import produce from immer and use the useImmerReducer hook to get started with computed properties in Immer and React.

#Immer #React